The present invention relates to a marine steering arrangement for effecting steering by actuating a hydraulic steering machine through remote manipulation, and more particularly, to a marine steering arrangement in which systems for actuating the steering machine are provided in at least two channels.
One marine steering arrangement in the prior art is illustrated in FIG. 1, in which a steering signal for a rudder, for steering either in the starboard direction, or in the port direction is applied from a bridge to a power unit 17 or 17' in a steering machine chamber through remote manipulation to cause a piston rod 17-2 or 17'-2 to move in a stroke in the direction of arrow a. This motion is transmitted and converted, via an intermediate rod 17-3, or 17'-3 to a manipulation arm system 15 as a rotational motion in the direction of arrow b.
It is noted that in this case, a pin 15-4 for coupling a manipulation arm 15-5 onto the side of a mechanical handle 16-1 is removed.
As a result, the rotary motion of the manipulation arm system 15 is converted into a linear motion in the direction of arrow c of a manipulation rod system 14, and is transmitted to a floating arm 13-1.
At this time, since the rotation of the floating arm 13-1 has a center of rotation about a fulcrum B, pump control rods 11-1 and 11'-1 are caused to move linearly in the direction of arrow d by the floating arms 13-2, 13-3 and 13-4.
As a result, control levers 1-3 and 1'-3 for controlling the discharge rates and discharge directions of variable discharge type pumps 1-1 and 1'-1, respectively, in the respective pump units 1 and 1', are rotated as shown by arrow e.
Accordingly, the pump 1-1 or 1'-1 discharges pressurized oil into pipes 9-1 or 9-2, respectively, and sucks the oil from pipes 8-1 or 8-2, respectively. The discharged pressurized oil is fed through pipes 9-3, 9-4 and 9-5 to hydraulic cylinders 2-1 and 2-2 so as to act upon rams 4-1 and 4-2, respectively.
Thereby the respective rams 4-1 and 4-2 undergo linear motion, and at the same time, the linear motion is converted into a rotational motion, in the direction of arrow f, by a tiller 5. Further, the rotational motion is transmitted to a rudder axle 7 via a rudder axle key 6, and as a result, a rudder plate is rotated in the direction of arrow f.
In addition, oil within hydraulic cylinders 3-1 and 3-2 is discharged through pipes 8-1 through 8-5 due to the linear motion of the rams 4-1 and 4-2, and is sucked by an operating pump 1-1 or 1'-1.
Further, the rotational motion of the tiller 5 is also transmitted to a tracing rod 10 which has a spring 10a, associated therewith, and its linear motion in the direction of arrow g is converted into the rotational motion of the floating arm 13-1 about a fulcrum at point A. This results in pump control rods 11-1 and 11'-1 moving linearly in the direction opposite to arrow d by means of the floating arms 13-2 through 13-4, so that the pump control levers 1-3 and 1'-3 are returned to their neutral positions.
In response to the restoration of the respective pump control levers 1-3 and 1'-3 to their neutral positions, the pump 1-1 or 1'-1 stops its discharge-suction effects, and as a result, the rotation of the tiller 5 is stopped.
More particularly, the rudder is steered by an amount corresponding to the steering command signal which is issued from the bridge and transmitted to the marine steering arrangement from the bridge (the magnitude of stroke of the piston rod 17-2 or 17'-2 of the power cylinder 17-1 or 17'-1).
It is noted that in the case where the piston rod 17-2 or 17'-2 in the respective power unit 17 or 17', is actuated in the direction opposite to arrow a, the operation can be explained exactly in the same manner as before.
In addition, in the situation case where steering is effected by means of the mechanical handle 16-1 in the steering machine chamber, the pin 15-3 is removed after the pin 15-4 has been inserted, and by rotating the mechanical handle 16-1 in the direction of arrow h, a threaded shaft 16-2 in a mechanical handle transmission system 16 is rotated. As a result, the manipulation arms 15-5 and 15-1 can thus be rotated in the direction of arrow b. It is further noted that the operation of the other mechanical control means associated with the aforedescribed mechanical handle operation, is similar to that in the case of the remote manipulation.
However, in the type of marine steering arrangement shown in the prior art, although there are provided pump units 1 and 1' for a steering machine, associated devices including power units 17 and 17', remote manipulation devices from a bridge, and piping systems, in two channels which include a spare channel, a mechanical control means (manipulating and tracing means) which connects the power units 17 and 17', in these remote manipulation devices, to the pump units 1 and 1', respectively, for the steering machine, is not available in the two channels. More particularly, except for the intermediate rods 17-3 and 17'-3 which are connected to the piston rods 17-2 and 17'-2 for the power units, and the control rods 11-1 and 11'-1 which are connected to the pump control levers 1-3 and 1'-3, the mechanical means such as the floating arm system 13, manipulation rod system 14, and manipulation arm system 15, etc., are found only in one channel. As a result, if any problems occur in these systems, it would become impossible to control the pump 1-1 or 1'-1 and thereby, steering would become impossible. Thus there is a possiblity of causing a serious accident such as the collision of ships.
Accordingly, although a 2-channel system having a spare circuit which includes remote manipulation means, hydraulic pump units 1 and 1', etc., is employed as described above, if the manipulating and tracing means in the mechanical control means for coupling these control systems is provided in only one channel and not in a spare channel, then the efficacy of the aforedescribed two channels wil be reduced, and further, if the entire steering system comprises a mere two channels assembled in parallel, then there exists a problem that even if only one unit in the channel should become faulty, the entire channel with which the faulty unit is associated would become impossible to use, and so, the relative importance of a trouble in one unit would become very large.